Skidabrader Anti-Skid Process Textures Longest Bridge In The World

Lake Pontchartrain Causway's original concrete decks have survived the elements and traffic volumes that now exceed 30,000 vehicles daily.

The Skidabrader at work texturizing the lake Pontchartrain Bridge.

The Skidabrader, a machine manufacturered by Humble Equipment Company.

Back in the 1950's the Louisiana parishes of St. Tammany and Jefferson voted to construct a 24 mile-long, two-lane bridge across Lake Pontchartrain.

The new bridge opened for business in 1957. Eleven years later, a separate, two-lane, parallel bridge was built to handle the increase in traffic.

But for a few patches here and there, the Lake Pontchartrain Causeway's original concrete decks have survived the elements and traffic volumes that now exceed 30,000 vehicles daily. In 1998, with 30 to 40 years of wear and tear, the Greater New Orleans Expressway Commission (GNOEC), current caretaker of the bridge decided it was time for a facelift.

"We increased the commuter toll for $1 to $1.50 to cover the $60 million cost of the work," stated Bryan Clement, director of engineering for GNOEC. "Over the next nine years, the bridge will be seeing a lot of renovation, from call boxes and striping to piling reinforcement and work on the deck itself."

Outflow meter test.

This project included removal and replacement of 120,000 pavement markers, spall repairs, permanent signage and restriping of both north- and south-bound decks following a texturing process designed to increase wet weather skid resistance and prevent hydroplaning. The spec called for texturing the concrete bridge deck surfaces by abrading the surface with a high velocity impact method to expose the aggregate and provide drainage channels beneath the tire contact points.

The texturing portion of the job was awarded to subcontractor Humble Equipment Company of Ruston, LA, developer of the Skidabrader, a process that is rapidly gaining the attention of the industry.

Removed material from this project was recycled as fill which provided that mase material for an expanded employee parking lot at the northern terminus of the bridge.

Skidabrader has done a lot of high profile work around the country including the shuttle runway for National Aeronautic and Space Administration (NASA), major airport runways, tunnels and interstates.

The job called for texturing of the concrete surface to a minimum average surface depth of 0.050 inch or greater at a rate of 1,500 square yards per hour. Testing was to include 40-mph skid tests in accordance with ASTM E-274, sand patch tests in accordance with Louisiana DOTD617 and FJHWA-type outflow meter test. Skidabrader passed all the tests with flying colors. Riley Boudreaux, field inspector for the Aims Group, Inc., a consulting engineering company, confirms those results.

Boudreaux, a retired Department of Transportation (DOT) highway inspector with over 34-years experience, monitored the testing procedures over the almost 100 lane miles of the Lake Pontchartrain project. "We ran the sand patch and outflow meter tests every tenth slab and they were well within specs across the bridge." 843 sand patch tests averaged 0.054" and 2,350 outflow meter tests averaged 3.92 seconds. Skid tests showed comparable improvements in the skid resistance of the concrete. "I was impressed with the results," said Boudreaux. "Skidabrader provided a printout of the prior day's testing each morning. These people really have their act together. And I was really impressed with the cleanliness of the jobsite."

Sand patch test.

Boudreaux was referring in part to the Skidabrader's self-cleaning process. As material is removed from the deck, it is stored in a truck that disconnects from the high-velocity impact unit for transport and dumping. Removed material from this project was recycled as fill which provided the base material for an expanded employee parking lot at the northern terminus of the bridge.

The renovation project included 782,000 square yards of surface to be textured and restriped in 150 days. Skidabrader was in and out in 25 working days and striping and marking phase bow complete, 90 days ahead of schedule.

Humble Equipment designed and manufactured the three Skidabrader machines used on the project. They include the high-velocity systems that allow the operator to fine tune the velocity, attack angle and machine speed for the best combination of end result and cost-effectiveness. The Skidabrader process is a unique combination which reduces the cost of texturing both concrete and asphalt surfaces on large scale roads, bridges, and airport runway projects.

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